It’s In The Genes - The Epigenetic Landscape

Previously I discussed the biological basis for inheritance of traits that are passed down through genes from our parents that give us the similarities we expect between parents and children.  The whole of a person is made up of millions and millions of tiny cells which function in different ways in groups called tissue but are linked by carrying the exact same sequence of DNA, deoxyribonucleic acid, in each.  Even though each cell has the same sequence of DNA, the remarkable thing is that each cell uses that DNA in a different way.  Imagine a massively long list of words, and each word is a code that means something; the words are like genes - they mean something - but only if you know what to do with them and how they fit together. 

This is what we’ve known for a while now - describing how genes are turned on and off in different areas throughout the body.  For example the incredulous fact that a baby formed from just half of its mothers DNA (an egg) and half of its father’s DNA (a sperm) and comes out as a whole perfect baby an orchestrated symphony of gene expression that can only make you wonder.   However, the mystery continues to deepen, as genes are not really fixed, though they also are as we discussed last time.  Often when something is really worthy of reflection, two seemingly opposing things are true at the same time. 

Epi- is the suffix that means upon, so Epigenetic means what’s above or on top of the genes, and it is physically composed of different biological parts.  This aspect of the cellular machinery and genetic expression is what turns off and on different genes and what tells the body to make more or less of certain proteins, for example.  Since the cells in our body are constantly replicating themselves and then dying, these changes can actually be passed on to the child cells all the time.  The most amazing thing is that this epigenetic process or landscape in the body is highly modifiable and there is lots of new and exciting research into how specific genes are turned on and off and how this affects risk for disease.  Probably the easiest example to help us realize how fluid our genes really are is that of identical twins.  Though their DNA is identical in content and sequence, since they are created from the same egg and sperm which divides an extra time to create two embryos, twins can develop very different diseases and even change to look different as they age.  In fact, there is also plenty of epigenetic activity going on in the womb as babies develop.  

Epigenetic factors have been linked to cancers.  For example we have genes that code for the p glycoprotein pump. This pump moves certain substances out of the cell and can be over expressed in cancer cells that are resistant to drugs. So the cancer cell pumps out the drugs that are intended to kill it.  Some botanicals can alter this by decreasing the expression of the p glycoprotein; these botanicals are therefore acting in an epigenetic way.  Other genes code for tumour suppressor genes, when they are turned on we have greater cellular protection against a cancerous cell continuing to replicate.  If these genes get turned off we loose some of that protection.  We could inherit a deficit in a gene like this or we could be exposed to toxic chemicals that alter the epigenetic landscape inhibiting the functioning of the gene. These are just a few examples of how fluid and changeable how genetic expression is and I’m looking forward to sharing more about epigenetics and the mysteries of memory next time.